Tripot universal joint of the end motion type

ABSTRACT

A tripot universal joint of the end motion type is provided. The joint includes a first shaft with a cup-shaped member at one end having three axially-extending, parallel grooves in its inner periphery. Another shaft has a spider at one end with three trunnions extending radially outwardly. A roller is mounted on each trunnion for slidable, rotatable, and pivotal movements with respect to the trunnion. The roller is maintained with its axis perpendicular to the associated groove, even when the spider shaft is positioned at a substantial angle to the axis of the first shaft and the cup-shaped member. The roller mounting includes a guide ring slidably mounted on the trunnion for axial movement with respect thereto, the guide ring having an outer segmental spherical surface. Bearings having surfaces formed by a curved generatrix with a radius extending away from the longitudinal axis of the bearings and being substantially equal to the radius of the spherical surface of the guide ring are located around the guide ring which forms an inner race. The roller is positioned around the bearings and forms an outer race. The annular surface of the roller adjacent the bearings can be curved in transverse cross section to fully support the bearings. The surface can also be flat in transverse cross section to support end portions of the bearings. In that instance, the bearings having generally cylindrical end portions engaged by the flat surface of the roller for support.

This is a division of application Ser. No. 706,670, filed Feb. 28, 1985,now U.S. Pat. No. 4,589,856.

This invention relates to a tripot universal joint with improved meansfor mounting rollers on trunnions for slidable, rotatable, and pivotalmovement thereon.

Most tripot universal joints of the end motion type have had rollersmounted on trunnions of a spider for only slidable and rotatablemovement with respect thereto. Universal joints of this type include afirst shaft with a cup-shaped member at one end having threeaxially-extending, parallel grooves in the inner periphery. The jointhas a second shaft with a spider at one end from which three trunnionsextend radially outwardly, with rollers mounted on the trunnions in amanner to allow axial and rotational movement of the rollers relative tothe trunnions. With these universal joints, as the angle between thefirst and second shafts increases, the rollers are correspondingly atgreater angles to the grooves, resulting in excess slippage which causesproblems such as friction, heat generation, vibration, and loss ofpower.

Attempts have been made heretofore to mount the rollers on the trunnionsfor pivotal or rocking movement as well as slidable and rotatablemovement. Such attempts are shown in U.S. Pat. No. 3,332,256, issuedJuly 25, 1967; U.S. Pat. No. 3,333,440, issued Aug. 1, 1967; U.S. Pat.No. 4,091,641, issued May 30, 1978; and U.S. Pat. No. 4,192,154, issuedMar. 11, 1980. The roller mounts shown in these patents have tended tohave certain deficiencies, such as being structurally weak, impractical,or requiring too many parts, resulting in excessive tolerancevariations, high costs, and assembly problems.

A universal joint of the sliding or end motion type in accordance withthe invention includes trunnions with guide rings slidably mountedthereon and having outer, segmental spherical surfaces. Bearings arelocated around each guide ring which forms an inner race and a roller ispositioned around the bearings and forms an outer race. The bearings areof circular transverse cross section through their length and ofdiminishing diameter from outer end portions to an intermediate portion.More specifically, the bearing surfaces are formed by a curvedgeneratrix with a radius extending away from the longitudinal axis ofthe bearing and being substantially equal in length to the radius of thesegmental spherical surface of the guide ring. The bearings can alsohave cylindrical end portions and two rows of bearings can be providedaround the guide ring, if desired. The guide ring and bearings are theonly components required for mounting the roller on the trunnion forslidable, rotational, and pivotal or rocking movement.

It is, therefore, a principal object of the invention to provide atripot universal joint of the end motion type having an improvedmounting arrangement for mounting rollers on trunnions of the joint forslidable, rotational, and pivotal movement with respect to thetrunnions.

Many other objects and advantages of the invention will be apparent fromthe following detailed description of preferred embodiments thereof,reference being made to the accompanying drawings in which:

FIG. 1 is a somewhat schematic, fragmentary view in elevation, withparts broken away and with parts in section, of a tripot universal jointembodying the invention;

FIG. 2 is a greatly enlarged view in transverse cross section takenthrough part of the universal joint of FIG. 1 but with a trunnion beingdisposed perpendicular to a groove of the joint;

FIG. 3 is a view in transverse cross section to part of a slightlymodified mounting arrangement for mounting rollers on trunnions;

FIG. 4 is an enlarged view similar to FIG. 3 to another slightlymodified mounting arrangement; and

FIG. 5 is a view similar to FIG. 4 of still another slightly modifiedmounting arrangement.

Referring particularly to FIG. 1, a tripot universal joint of the endmotion type embodying the invention is indicated at 10. The joint 10includes a first shaft 12 having a cup-shaped member 14 at one end, themember having a closed end 16 and an open end 18. The cup-shaped member14 has a plurality of, in this instance three, axially-extending,parallel grooves 20 extending from the open end 18 toward the closed end16 and uniformly spaced around the inner periphery of the member 14.

A second shaft 22 of the joint 10 has a spider 24 at one end, with a hub26 affixed to that end and with three trunnions or pods 28 extendingradially outwardly therefrom.

As shown more particularly in FIG. 2, the trunnion 28 has a guide ring30 slidably mounted thereon with an inner bore or passage 32 having across-sectional shape similar to the shape of the trunnion 28. The guidering 30 has an outer, segmental spherical surface 34, as viewed inlongitudinal section. The radius of the spherical surface 34 of theguide ring 30 has a center which lies on the axis of the trunnion 28.

Bearings 36, there being typically eighteen of them, are disposed aroundthe guide ring 30 which forms, in effect, an inner race for thebearings. Each of the bearings 36 is circular in transverse crosssection and has an outer surface 38 of diminishing diameter from outerend portions to a central or intermediate portion. The surface 38 can beformed by a curved generatrix having a radius extending away from thelongitudinal axis of the bearing and being substantially equal in lengthto the radius of the segmental spherical surface 34 of the guide ring30, with the center of the radius being on the axis of the trunnion 28.As shown, the bearings 36 also have generally cylindrical end portions40 and 42.

A roller 44 is located around the bearings 36 and the guide ring 30,forming an outer race for the bearings. The roller 44, in this instance,has an inner, annular groove 46 which has an intermediate arcuateportion 48 of the same radius as the roller surface 38 and hascylindrical end grooves 50 and 52 which receive or provide clearance forthe cylindrical end portions 40 and 42 of the bearings 36. The roller 44also has an outer or peripheral surface 54 having a shape similar to theshape of side walls 56 of the groove 20. In this instance, both are ofsegmental spherical shape, The roller 44 also has an annular extension58 extending beyond the bearings 36 and the guide ring 30 and forming aflat annular surface 60. This surface can contact a bottom wall 62 ofthe groove 20 to maintain the axis of the roller 44 generallyperpendicular to the longitudinal extent of the groove 20.

A slightly modified mounting arrangement shown in FIG. 3 includes theguide ring 30 and modified bearings 64. The bearing 64 has an outersurface 66 similar to the surface 38 of the bearing 36, with thissurface substantially fully engaging the segmental spherical surface 34of the guide ring 30. The bearing 64 also has generally cylindrical endportions 68 and 70 which are wider than the corresponding surfaces 40and 42 of the bearing 36.

A slightly modified roller 72 forms an outer race for the bearings 64and has an inner, annular groove 74. The groove 74, in this instance,has an intermediate cylindrical portion 76 with annular end shoulders 78and 80. While the groove 46 of the roller 44 fully backs up theperipheral surfaces of the bearings 36 along a line diametricallyopposite the line of contact of the bearings with the guide ring 30, theflat cylindrical surface 76 of the annular groove 74 only supports thecylindrical end portions 68 and 70 of the bearings 64. However, thewider cylindrical end portions 68 and 70 provide more support for thebearings than their counterparts in FIG. 2. Further, the groove 74 iseasier to machine or otherwise form than the groove 46 of FIG. 2.

Another slightly modified mounting arrangement is shown in FIG. 4. Inthis instance, the guide ring 30 can again be used. Two rows of bearings82 and 84 are in contact with the segmental spherical surface 34 of thering 30 which again forms an inner race for the bearings. The bearings82 and 84 can be identical but are smaller in diameter at one end thanthe other, unlike the bearings 36 and 64 of FIGS. 2 and 3. The bearings82 and 84 have curved outer surfaces 86 which can be generated similarto the surfaces of the bearings 36 and 64 but with one end larger thanthe other. The bearings 82 and 84 have smaller, generally cylindricalend portions 88 at one end and larger generally cylindrical end portions90 at the other end. More precisely, both end portions are of truncatedconical shape. As shown, lines extending through the end portions 88 and90 and an axis of the bearing 82 or 84 terminate at a common point orextrapolated apex which lies on the axis of the trunnion 28.

A roller 92, in this instance, has a main annular groove 94 in which areformed two narrower annular grooves 96 and 98, each having anintermediate arcuate portion 100 of the same radius as the rollersurfaces 86 and end grooves 102 and 104 which receive or provideclearance for the generally cylindrical end portions 88 and 90 of thebearings 82 and 84.

A further slightly modified mounting arrangement is shown in FIG. 5. Inthis instance, the guide ring 30 can form an inner race for bearings 106and 108 which can be identical. These bearings have curved outersurfaces 110 similar to the surfaces 86 of the bearings 82 and 84.However, the bearings 106 and 108 have wider generally cylindrical endportions 112 and 114, the latter being larger in diameter than theformer, and with both being more precisely of truncated conical shape.

A roller 116 forms an outer race for the bearings 106 and 108, having amain annular groove 118 and two narrower grooves 120 and 122. Thegrooves 120 and 122 have annular, conical surfaces 124 which are flat asviewed in transverse cross section and do not back up the surfaces 110of the bearing 106 and 108 as do the arcuate portions 110 of the grooves96 and 98 of FIG. 4. The grooves 120 and 122 also have end shoulders 126and 128 to aid in confining the bearings 106 and 108. While the grooves120 and 122 do not fully support the bearings, the wider cylindrical endportions 112 and 114 provide greater support than the cylindrical endportions 88 and 90 of the bearings 82 and 84. Further, the grooves 120and 122 in the main annular groove 118 are easier to machine orotherwise form. The roller 116, in this instance, has a cylindricalouter surface 130 for a groove 132 having straight side walls. Theroller 116 also has an annular groove 134 which cooperates with ashoulder or ridge 136 on the groove 132 to maintain the perpendicularposition of the roller relative to the groove. Other configurations canalso be used to accommodate the particular position of the rollerrelative to the groove.

From the above, it will be seen that the tripot universal jointaccording to the invention has a number of advantages over thoseheretofore known. The roller mount enables the roller to always bemaintained with its axis perpendicular to the longitudinal extent of thegroove in which it is received, regardless of the angles between theshafts of the joint. The roller mount is structurally strong and, inparticular, requires fewer number of parts or components so that costsare reduced, assembly problems are minimized, and previous excessivetolerance variations are overcome.

Various modifications of the above-described embodiments of theinvention will be apparent to those skilled in the art and it is to beunderstood that such modifications can be made without departing fromthe scope of the invention, if they are within the spirit and the tenorof the accompanying claims.

We claim:
 1. In a slidable universal joint of the end motion type havingan outer cup-shaped member, a plurality of generally axially-extendinggrooves positioned substantially parallel to one another in said member,a shaft having a spider affixed to an end portion thereof, said spiderhaving a plurality of radially-extending trunnions, there being one foreach of said grooves, a guide ring located on each of said trunnions forslidable movement therealong, a plurality of bearings located in tworows around each of said guide rings, each of said bearings being ofcircular transverse cross section throughout its length and having acontour, between outer end portions of the bearing, similar to a portionof the contour of the outer surface of said guide ring, with thesurfaces of said bearings between the outer end portions fullycontacting the outer surfaces of said guide rings, each of said bearingshaving a truncated conical end portion beyond each of said outer endportions, the truncated conical end portions of each of said bearingstapering in a common direction, a roller around each of said rings andsaid two rows of bearings, each of said rollers having two inner,annular grooves therein, one of which contacts and supports peripheralsurfaces of the bearings in one row and the other of which contacts andsupports peripheral surfaces of the bearings in the other row, thetruncated conical end portons of all of the rollers in one row taperingin a common direction opposite to the direction of taper of thetruncated conical end portions of the bearings in the other row.
 2. Auniversal joint according to claim 1 characterized by the truncatedconical end portions of the bearings in each row tapering to a commonextrapolated apex.
 3. A universal joint according to claim 2characterized by the common apex of the truncated conical end portionsof the bearing in one row lying in an opposite direction to the apex ofthe truncated conical end portions of the bearings in the other row andbeyond opposite ends of said guide ring.
 4. A universal joint accordingto claim 3 characterized by both of said apexes lying on the axis of theassociated trunnion.
 5. In a slidable universal joint of the end motiontype having an outer cup-shaped member with an open end and a closedend, a plurality of axially-extending grooves positioned substantiallyparallel to one another and extending toward the closed end from theopen end, a shaft having a spider affixed to an end portion thereof,said spider having a plurality of radially-extending trunnions, therebeing one for each of said grooves, a guide ring located on each of saidtrunnions for slidable movement therealong, each of said guide ringshaving an outer surface of segmental spherical shape, a plurality ofbearings located in two rows around each of said rings, each of saidbearings being of circular transverse cross section throughout itslength and of diminishing diameter from outer end portions to a centralportion, with the surfaces of said bearings between the outer endportions being contoured to fully contact the outer spherical surfacesof said guide rings, each of said bearings having a truncated conicalend portion beyond each of said outer end portions, the minimum diameterof one truncated conical end portion of one bearing being no smallerthan the diameter of the contiguous outer end portion and the maximumdiameter of the other truncated conical end portion of the same bearingbeing no smaller than the diameter of the the contiguous outer endportio of the bearing, whereby the truncated conical end portions ofadjacent bearings can contact one another during operation of theuniversal joint, the surfaces of said truncated conical portions beingspaced from the outer surfaces of said guide rings, a roller around eachof said rings and said two rows of bearings, each of said rollers havingtwo inner, annular grooves therein, one of which contacts and supportsperipheral surfaces of the bearings in one row and the other of whichcontacts and supports peripheral surfaces of the bearings in the otherrow, the truncated conical end portions of each of the bearings in onerow tapering to a common extrapolated apex and the truncated conical endportions of each of the bearings in the other row tapering to a commonextrapolated apex in the opposite direction of those in the one row. 6.A universal joint according to claim 5 characterized by both of saidapexes lying on the axis of the associated trunnion.
 7. A universaljoint according to claim 5 characterized by each of said inner, annulargrooves, as viewed in transverse cross section, having a flat bottomcontacting and supporting only the end portions of said peripheralsurfaces of said bearings.
 8. A universal joint according to claim 5characterized by each of said inner, annular grooves, as viewed intransverse cross section, having a contoured bottom contacting andsupporting all of the peripheral surfaces of said bearings.